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What is Saddle Thrombus

A couple of weeks ago, I mentioned that Meow Meow suffered from a complication of heart disease called saddle thrombus or FATE. Further, due to her condition, we decided to put her to sleep. But what is saddle thrombus? What are the signs? Does it affect dogs too? And can it be prevented? Continue reading as I answer these questions and more.

Distal aortic trifurcation thromboembolism, aortic thromboembolism, and saddle thrombus are all similar. And you’ll usually see them used interchangeably as well. Moreover, aortic thromboembolism or ATE is a deadly illness. Plus, when a blood clot or thrombus gets established in the aortic trifurcation, it extends down into the external iliac arteries. At that point, it ends up resembling a saddle. Thus, the term saddle thrombus.

Causes of Saddle Thrombus

black pug
Photo by Charles on

You already know that saddle thrombus occurs in cats. In fact, it’s more common in male cats than females. And although it’s rare for dogs, it does happen. Additionally, just as with cats, saddle thrombus is more prevalent in male dogs than females. However, saddle thrombus is usually caused by heart disease in cats, typically HCM. Though, with dogs, a variety of conditions can produce saddle thrombus, including

  • sepsis
  • cancer
  • cardiomyopathy aka heart disease
  • damage to the lining of a blood vessel
  • enlarged left atrium
  • heartworm
  • hyperthyroidism
  • iron deficiency
  • blood clotting issues
  • weakly performing heart
  • protein losing nephropathy (PLN)
  • and splenectomy

And according to this study, PLN was the most commonly diagnosed issue recognized to induce a hypercoagulable state. Therefore, it’s presumed there might be a connection between an increased tendency to develop blood clots caused by PLN and saddle thrombus formation.

Signs of Saddle Thrombus

Traits like unexpected paralysis, pain, respiratory distress, and sudden death can take place in both cats and dogs with acute onset of saddle thrombus. Despite that, it’s still rare for dogs to experience acute onset. Rather, canines are more likely to manifest symptoms of chronic onset of saddle thrombus compared to cats.

Signs of Acute Onset Saddle Thrombus in Cats and Dogs

black and white dog next to a calico cat on a brown couch

Since blood supply to hindquarters is blocked, both cats and dogs can experience

  • paralysis in one or both hind legs (cats)
  • back legs will be cold to touch
  • foot pads and nail beds may appear pale
  • cats will cry out or meow more
  • hypothermia
  • vomiting
  • possible respiratory distress
  • and sudden death
  • paralysis in one or both hind legs (dogs)
  • back legs will be cold to touch
  • foot pads and nail beds may appear pale
  • dogs bark and appear anxious
  • hypothermia
  • vomiting
  • possible respiratory distress
  • and sudden death

Symptoms of Chronic Onset Saddle Thrombus in Dogs

Chronic symptoms are more subtle and may only appear as weakness or limping. However, over time your dog may also present with

  • anxiety
  • coughing
  • trouble getting up or jumping
  • reduced ability to exercise or stamina
  • hypothryroidism
  • a limp due to weakness in back legs
  • lowered body temperature
  • toe wounds
  • sudden paralysis and pain
  • respiratory distress
  • weakness
  • and sudden death

How Saddle Thrombus is Diagnosed

man and woman looking at an ultrasound machine while Pomeranian is on a table
Photo by Tima Miroshnichenko on

Including the above signs, upon examination, femoral pulses on the inner upper back legs are typically absent on cats. And sometimes they’ll be absent on dogs. Therefore, a diagnosis of saddle thrombus can be made largely on symptoms alone. Given the gravity of the situation, most pet parents opt to euthanize their pets.

Otherwise, if treatment is still desired, more tests and diagnostics are required, such as

  • Xray
  • Ultrasound
  • Urinalysis (dogs)
  • ECG
  • and blood tests

Several factors should be considered when determining to pursue treatment rather than euthanasia. Issues that negatively impact survival with cats include

  • decreased heart rate
  • absence of motor function
  • having more than one leg affected
  • hypothermia
  • and a confirmed diagnosis of congestive heart failure (CHF)

And the main factor affecting survival with dogs is ambulatory status. For instance, dogs with aortic thromboembolism usually fare better if they are still walking compared to dogs who are paralyzed due to the same condition.

How to Treat Cats with Saddle Thrombus

tortoiseshell cat being treated at a veterinarian's office

Often cats need to be hospitalized for a week or two with saddle thrombus until stable. Additionally, they may be referred to a kitty cardiologist But, initially, treatment may consist of

  • pain medications
  • oxygen, if and when necessary, for CHF or respiratory distress
  • IV fluids for dehydrated cats
  • antithrombotic therapy, ie heparin
  • as soon as oral medicines are tolerated, then Plavix is started
  • next, when patient is stabilized and pain is under control, physical therapy of affected limbs is started

However, loss of blood flow to the hind leg can lead to tissue death. So, if only one leg is affected, amputation is an option. Though, there are some contingent aspects.

  • after patient is stable and comfortable, any necessary diagnostics for treating the underlying cause of saddle thrombus are carried out
  • and monitoring patient closely

How to Treat Dogs with Saddle Thrombus

veterinarian giving tan pit bull terrier injection of some medicine
Photo by Pranidchakan Boonrom on

As you’ll notice, much of the therapy offered to cats with saddle thrombus is similar for dogs as well. Nevertheless, there are a couple of differences, as you’ll see. In addition, treatment is not universal, which means it depends upon the veterinarian and their expertise. Therefore, if your dog has saddle thrombus, medical care might include

  • hospitalization, depending upon the severity of the patient’s condition
  • pain medications
  • oxygen therapy, if necessary
  • antithrombotic medication, such as heparin
  • aspirin and/or Plavix will also be started
  • although, if clotting isn’t broken up, then the patient may be referred to a specialist, or the veterinarian may opt to surgically remove the clot
  • and finally, treat the underlying cause of saddle thrombus

Outcomes with Cats and Dogs with Saddle Thrombus

black and grey cat with short hair on a white surface
Photo by Burak The Weekender on

Once cats and dogs have a saddle thrombus, the prognosis is very poor. Despite the effort, they’ll either end up not making it, or more than likely have another episode. Thus, most pet parents choose euthanasia for their pets as the most humane option of relieving their suffering. However, you will undoubtedly find instances online of pets who were discharged from the hospital or survived ATE. Though, from everything I’ve read, those examples are considered outliers.

For instance, this study, involving 250 cats that had FATE, revealed that over 150 of the cats were initially euthanized. The study followed the therapy, hospitalizations, deaths, and etc over a period of several months. Then, depending upon certain conditions, some of the cats survived up to a week. But, due to severity and other factors I’ve listed, many still didn’t make it. And others had 2 or even 3 additional occurrences of FATE. In the end, only 6 of the 250 cats survived.

And this one, regarding dogs with saddle thrombus, is similar, yet not as grim. It included 100 dogs at the beginning. But again, because of different issues, only 16 of the original 100 were still living half a year later.

Preventing Saddle Thrombus

a veterinarian checking a sick dog using a stethoscope
Photo by Tima Miroshnichenko on

Plavix is the recommended preventative treatment for saddle thrombus in at-risk cats. Though, many pet parents don’t know that anything is wrong with their cats until it’s too late. But that’s why vaccinations are a great time to see the vet. Moreover, if your pet has chronic issues, such as heart disease, CHF, or kidney disease, keeping up with visits is a necessity.

Although, there are things you can look out for as well, to be proactive. Since I know you care about your pets as much as I care about my own, I like to share the things I’ve hopefully learned. With Meow Meow dying, I look back on things I feel I should’ve noticed; things that make me question whether she was sick almost 2 years ago. But then I tell myself, Of course she was, silly! She had heart disease. Indications your cat might have an issue with their heart or be at-risk for saddle thrombus would be

  • water intake (drinking more than ~1 cup a day for an adult cat)
  • activity level has dropped significantly
  • appetite has changed as well or doesn’t eat as much.
  • losing weight
  • using the bathroom in places other than the litter box
  • panting or shallow breathing
  • stopped grooming themselves, ie. claws need trimming and they have dandruff
  • and/or periodic lameness in different limbs

Since I don’t know much about dogs with saddle thrombus, there wasn’t anything different online than what’s already listed. Yet, I feel like they would also present in some ways similar to a cat such as

  • activity level has changed, ie not doing as much or can’t do as much
  • appetite has changed, ie, doesn’t eat as much or eats more than before for an adult dog
  • weight gain or weight loss
  • panting or shallow breathing when not doing much exercise
  • periodic lameness in different limbs
  • low urine output compared to water intake
  • weakness
  • vomiting
  • and/or abnormal behavior

I based these symptoms on the conditions listed above that can cause saddle thrombus in dogs. Furthermore, if you’re concerned about your pet’s health, contact your veterinarian. The best prevention is early detection and treatment.

So, What is Saddle Thrombus

tortoiseshell shorthair cat asleep on a blue jacket next to window

Saddle thrombus can affect both cats and dogs. Although, it’s not as common with dogs as it is with cats. And while heart disease is the main culprit behind ATE in cats, there can be any of a number of issues in dogs. Moreover, dogs generally manifest chronic onset symptoms, whereas cats will have acute symptoms. Also, both cats and dogs are diagnosed and treated pretty similarly. However, veterinarians no longer surgically remove blood clots in cats.

In addition, both kinds of pets have a poor prognosis, depending on motor function. Furthermore, if cats have hypothermia, more than one limb affected, and CHF, that affects the outlook as well. But keep your pets’ annual visits with the veterinarian, so they can detect any changes. And if you notice anything out of the ordinary, please call the vet. I hope you never have to experience anything like that with your fur babies.

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